What is the difference between the third and fourth generation iPod models?
The fourth generation iPod, introduced July 19, 2004 and discontinued June 28, 2005, originally shipped with either a 20 GB or 40 GB hard drive, and from February 23, 2005 to June 28, 2005 shipped with just a 20 GB hard drive. The fourth generation is similar to the third generation models, but features a slightly thinner enclosure and an improved display, borrows the revolutionary “ClickWheel”, which places pressure sensitive navigation buttons under the scroll wheel, from the previously introduced iPod mini, and dramatically improves battery life for up to 12 hours of continuous music playback. In addition to improving battery life, revised software places the “Shuffle Songs” feature on the main screen, and includes the voice record feature, games, and an alarm clock from the third generation model. The original 40 GB configuration of the fourth generation shipped with a “dock” for quick-and-easy connection to a computer and could be purchased separately for the 20 GB configuration.
